Add the release-note-none to dependabot
Add the release-note-none to dependabot

Without the release label, dependabot PRs cannot be merged.
Altering the PR to add the label means that dependabot won't
be able to manage its PR anymore, so adding the release note
label by default.

Signed-off-by: Andrea Frittoli <4cec69a2e3f23b658ef5550bf7c5b5012f9473f7@uk.ibm.com>

tektoncd/pipeline,tektoncd/pipeline